Rojo will reportedly cost £16 million (€20m) and Sporting will receive 20% of the profits if United sell him on for more than £18.4m (€23m). He will become United's third major signing of the summer after the arrivals of Luke Shaw and Ander Herrera.

United turned to the Argentina international after accepting defeat in their attempts to sign Dortmund's Mats Hummels and Thomas Vermaelen, who joined Barcelona.

United have been short of defenders following the summer departures of Rio Ferdinand, Nemanja Vidic and Patrice Evra and manager Louis van Gaal's decision to switch to a formation that requires three centre-backs.